Hettar

I just finished a rebuild on my 289 and put it back in the car. I'm trying to crank it and it's backfiring and spitting fire out the carb. True, it's really colorful to watch at night, but I'd rather drive it. Anyway, I've checked and rechecked my plug wires to make sure they're not crossed and they look good. I've pulled the #1 plug out, and pulled the distributor off and, while having someone turn over the engine, put my finger over the spark plug hole and watched where the rotor was positioned when the compression pushes my finger off the hole... and it looks to be at the #1 post when it compresses.

I've got a couple of ideas at the moment... one, I replaced my distributor cap with an Accel Super Stock one during the rebuild and it fits pretty sloppy. I'm going to stop by the autoparts store this evening and get just a stock cap/button and see if that's the problem.

Two, I'm wondering if I have my timing chain 180 degrees off, will the #1 compression still match up with the #1 firing time, but some of the other cylinderswon't? I'm going to try and test out a couple more cylinders this evening to see if that's the case.

Three, I figure it's a slim chance, but I changed the stock cam out with a Edelbrock Performer RPM cam during the rebuild and wondering if I might have the wrong cam in. Dang, I hope not.

Anyway, if anyone has any suggestions on some other ways to figure out what's causing all the fireworks, I'd sure appreciate some ideas.

Thanks.

P Zero

Your disty is 180* off.
-P.

Grimm

+ 1 on the disty. When it's coming up on what you think is the compression stroke it is actually the exhaust stroke

Soaring

Is the rotor pointing at the 1:00 O'Clock position on the distributor when the #1 piston is at the top? Or, is it pointing at the 7:00 O'Clock position?

Hettar

1:00 O'Clock when the compression blows my finger off the hole.

For the other replys, Ithought on the exhaust stroke, the exhaust valve should be open and so, there'd be no pressure blowing through the spark plug hole at that point.

...and thanks for the replys!!

Soaring

If you are absolutely positive you have static timed it correctly, then let's go back and double check the firing order.
15426378


4 8
3 7
2 6
1 5
Front

If that checks out, then go back and double check the procedures you used to install the timing chain. It may have slipped a cog.

my77stang

its worth double checking the cam's firing order. some aftermarket cams use the 351w / later 302 firing order(1-3-7-2-6-5-4-8) , which is actually supposed to be better.

but +1 on the dizzy, thats always first culprit

Soaring

Very valid point Shane. Yeah, try the 351 firing order if the 289 firing order doesn't work, and you have static timed it correctly, and the timing chain is where it should be.

ZZmustang

With theno. 1pistonvalve cover off, use the started to rotate the engine. after the intake valve goes down and back up check the timming mark on the damper. when it is at zero. The roter should be pointing at the Number one spark plug wire. If it's not move the distributer until it does. then wire the fireing order. for a 289 cam. If it still miss fires check the cam, 351 windsor had diferent fireing order like someone said. Don't back fire the engine, this may bend rods or valves.

my77stang

what kinda carb you running on there? a single backfire can wipe out the power valve on an older holley (cheaply replaced) - the newer ones have blowout protection though


damn, they know my name *Shane ducks and runs*